In a computer that includes a dynamic random access memory (DRAM) as a memory and includes a hard disk drive (HDD) as a storage device, an input/output (I/O) speed of the HDD is lower than an I/O speed of the DRAM. Therefore, cache technology for storing partial data in the HDD in a cache area of the DRAM and reading data from the cache area, not the HDD, when data of a read target exists in the cache area of the DRAM, has been known (refer to PTL 1). Thereby, when a cache is hit, the data can be read at a high speed, as compared with when the data is read from the HDD.
In addition, the DRAM has a work area in which data such as an application program is stored, in addition to the cache area. Because a storage area of the DRAM is limited, technology for providing a swap area becoming a saving destination of the data in the work area in the HDD in preparation for the case in which the work area is insufficient has been known.